[4] Mr. Tylor (`Primitive Culture,' 1871, vol. i. p. 166), in his
discussion on this subject, alludes to the whining of the dog.

[5] `Naturgeschichte der Saugethiere von Paraguay,' 1830, s. 46.

[6] Quoted by Gratiolet, `De la Physionomie,' 1865, p. 115.

"It is on this RELATIVE association of the sounds that all the
essentially characteristic effects which are summed up in the phrase
`musical expression,' depend. But why certain associations of
sounds have such-and-such effects, is a problem which yet remains
to be solved. These effects must indeed, in some way or other,
be connected with the well-known arithmetical relations between
the rates of vibration of the sounds which form a musical scale.
And it is possible--but this is merely a suggestion--that the greater
or less mechanical facility with which the vibrating apparatus
of the human larynx passes from one state of vibration to another,
may have been a primary cause of the greater or less pleasure
produced by various sequences of sounds."

But leaving aside these complex questions and confining ourselves
to the simpler sounds, we can, at least, see some reasons for the
association of certain kinds of sounds with certain states of mind.
A scream, for instance, uttered by a young animal, or by one of
the members of a community, as a call for assistance, will naturally
be loud, prolonged, and high, so as to penetrate to a distance.
For Helmholtz has shown[7] that, owing to the shape of the internal
cavity of the human ear and its consequent power of resonance,
high notes produce a particularly strong impression. When male
animals utter sounds in order to please the females, they would
naturally employ those which are sweet to the ears of the species;
and it appears that the same sounds are often pleasing to widely
different animals, owing to the similarity of their nervous systems,
as we ourselves perceive in the singing of birds and even
in the chirping of certain tree-frogs giving us pleasure.
On the other hand, sounds produced in order to strike terror
into an enemy, would naturally be harsh or displeasing.

Whether the principle of antithesis has come into play
with sounds, as might perhaps have been expected, is doubtful.
The interrupted, laughing or tittering sounds made by man and by
various kinds of monkeys when pleased, are as different as possible
from the prolonged screams of these animals when distressed.
The deep grunt of satisfaction uttered by a pig, when pleased with
its food, is widely different from its harsh scream of pain or terror.
But with the dog, as lately remarked, the bark of anger and that of
joy are sounds which by no means stand in opposition to each other;
and so it is in some other cases.

There is another obscure point, namely, whether the sounds which are
produced under various states of the mind determine the shape of the mouth,
or whether its shape is not determined by independent causes, and the sound
thus modified. When young infants cry they open their mouths widely,
and this, no doubt, is necessary for pouring forth a full volume of sound;
but the mouth then assumes, from a quite distinct cause, an almost
quadrangular shape, depending, as will hereafter be explained, on the firm
closing of the eyelids, and consequent drawing up of the upper lip.
How far this square shape of the mouth modifies the wailing or crying sound,
I am not prepared to say; but we know from the researches of Helmholtz
and others that the form of the cavity of the mouth and lips determines
the nature and pitch of the vowel sounds which are produced.

[7] `Theorie Physiologique de la Musique,' Paris, 1868, P. 146.
Helmholtz has also fully discussed in this profound work the relation
of the form of the cavity of the mouth to the production of vowel-sounds.

It will also be shown in a future chapter that, under the feeling
of contempt or disgust, there is a tendency, from intelligible causes,
to blow out of the mouth or nostrils, and this produces sounds
like pooh or pish. When any one is startled or suddenly astonished,
there is an instantaneous tendency, likewise from an intelligible cause,
namely, to be ready for prolonged exertion, to open the mouth widely,
so as to draw a deep and rapid inspiration.